Many treatments for this chronic skin disease are harmful to the developing fetus, so careful pre-conception planning and management adjustment are crucial for the pregnant patient

Psoriasis is a common skin condition that causes considerable morbidity and occupational disability.w1 It has an estimated lifetime prevalence of 1.5-2.2% in the adult population,1w2 with three quarters of patients presenting before the age of 40.w3 Incidence is similar for the two sexes, although women generally develop the disease earlier than men. The prevalence in pregnant women is unknown but probably reflects that of non-pregnant women of child bearing age. The scenario box on this page shows that balancing treatment of severe psoriasis with the decision to try to conceive requires forward planning, and there is always a chance that the disease will worsen. Our patient was fortunate to become pregnant so quickly; less fortunate women can have a prolonged and difficult course and must decide how long they will try to conceive before resuming systemic treatment.

Scenario

A 30 year old woman had had chronic plaque psoriasis since childhood. She had previously needed a prolonged course of PUVA (psoralen and ultraviolet A) and two admissions to achieve control of her psoriasis. She then began intermittent treatment with methotrexate, followed by continuous treatment. When she had been taking methotrexate for five years she decided she wanted to start a family. She therefore stopped methotrexate and took the oral contraceptive pill for three months. Within four weeks of stopping methotrexate her psoriasis flared up but was controlled with an eight week course of narrowband ultraviolet B. The patient became pregnant with twins four months after stopping methotrexate but has needed further ultraviolet B to control her psoriasis throughout pregnancy.

Methods

We searched national health information sources, the British Association of Dermatologists guidelines, the …